scholarly journals First detection of Mnemiopsis leidyi (Ctenophora, Bolinopsidae) in Sardinia (S’Ena Arrubia Lagoon, Western Mediterranean): a threat for local fishery and species recruitment

2016 ◽  
Vol 17 (3) ◽  
pp. 714 ◽  
Author(s):  
R. DICIOTTI ◽  
J. CULURGIONI ◽  
S. SERRA ◽  
M. TRENTADUE ◽  
G. CHESSA ◽  
...  
Keyword(s):  
Management Strategies ◽  
Anguilla Anguilla ◽  
Western Mediterranean ◽  
Economic Damage ◽  
Mnemiopsis Leidyi ◽  
European Eel ◽  
Fishing Activity ◽  
Western Atlantic ◽  
Management Measures ◽  
First Time

The invasive comb jelly Mnemiopsis leidyi is a lobate ctenophore native of coastal and estuarine waters of the temperate western Atlantic Ocean. In the last decades this species has expanded its range of distribution, colonizing marine and transitional environments in Europe. In October 2015, during a survey fishing the European eel Anguilla anguilla in Sardinia (western Mediterranean), a massive bloom of this specie was observed in the eutrophic S’Ena Arrubia Lagoon for the first time. In November 2015, sampling was conducted at three stations in the lagoon and in a fyke net, in order to estimate the abundance of M. leidyi and to determine its impact on the fishing activity. The results showed an abundance of 2.83 ctenophores m-3. Specimens were all adults, measuring 18 - 62 mm total length. The abundant number of ctenophores (6837 individuals per fyke net) damaged fishing operations, reducing catches and affecting the performance of fishing gears. Since there is no effective mechanical, chemical or biological method to counter M. leidyi, the short term economic damage may be approached by new management measures of fisheries. In addition, other actions against the recurring of M. leidyi invasion, can include management strategies, in particular those finalized to reduce the high trophic state of the lagoon. 

Eels at the Edge: Science, Status, and Conservation Concerns

2009 ◽  
Keyword(s):  
Management Strategies ◽  
Anguilla Anguilla ◽  
Fish Stock ◽  
European Eel ◽  
Stock Management ◽  
Management Measures ◽  
Management Scheme ◽  
Spawning Stock ◽  
Almost All ◽  
Short Time

<em>Abstract.—</em>The stock of the European eel <em>Anguilla anguilla </em>is in a critical state. A prolonged downward trend in landings since 1960 suggests a steady decline of the continental stock, while incoming recruitment fell to record low levels in the 1980s over almost all of Europe. Although the effect of oceanic factors cannot be ruled out, continental processes that have depleted the spawning stock are the most likely cause of the decline. Management strategies that are successful with other fish stocks may not work well for eels. An innovative management scheme that preserves adequate spawner production is urgently required. This paper examines the specific problems of the eel and proposes a solution from existing concepts in fish-stock management. It covers the problem of the wide and scattered distribution, the inability to set targets for the oceanic life stages, the distribution of responsibilities among management levels, the need to adapt management measures to local and time-varying (environmental) conditions, and the short time left to develop and implement a complex management system that achieves a sustainable regime. A conceptual framework for restoration of the declining European eel stock being outlined, progress in management and restoration of the eel is now a matter of political decisions.

scholarly journals Fishery and Aquaculture Relationship in the Mediterranean: Present and Future

2003 ◽  
Vol 4 (2) ◽  
pp. 125 ◽  
Author(s):  
G. RELINI
Keyword(s):  
Anguilla Anguilla ◽  
European Eel ◽  
Total Catch ◽  
Sharp Drop ◽  
Fishing Activity ◽  
Marine Fauna ◽  
Marine Research ◽  
The World ◽  
The Mediterranean ◽  
Aquaculture Production

Although the Mediterranean represents only 0.8% of the world seas, it is the site of a very long-established fishing activity, characterized mainly by multispecific catch and by artisanal or coastal activity, resulting from a mosaic of very diversified structures and gears, along more than 45,000 km of coastline. Two main biological features of this sea are the occurrence of a large richness of species (it represents 5.5% - 7% of world marine fauna and 16.6% of macrophyta), which stands in contrast with its ‘trophic poverty’ and the absence of large monospecific fishery, except for some small and large pelagic fish. Another biological characteristic of Mare Nostrumis the high invasion of exotic species, some exploited by fishery and aquaculture, some others quite dangerous. For the entire Mediterranean and Black Sea, the production (catch + aquaculture) had been steadily increasing over the period 1972-1988 from 1,140,000 t to 2,080,000 t . The period 1988-1991 has shown a drastic drop in catches (in 1991: 1,400,000 t). From 1990 to 1995 the total catch increased to 1,701,379 t then decreased and in 2000 reached 1,485,046 t . In 2000 Turkey had the first place with 496,174 t, 26.9% of the total value (1,846,026 t, including fishing and aquaculture), followed by Italy with 25%, Greece 9%, Spain 7.6% and Algeria 5.4%. As in many parts of the world, aquaculture production in the Mediterranean is rapidly expanding. In 1970 the total aquaculture production was about 18,297 t of which 74.3% produced in Italy. In 2000 a value of 358,614 t was reached, about 1/4 of the total fishery catch, while the world aquaculture production corresponds to half of the world total catch. Italy is still the main producer with 46.7% , followed by Greece with 21.5%, Turkey 9.9% and France 6.7%. A sharp drop in the production of the European eel ( Anguilla anguilla) and of the European flat oyster ( Ostrea edulis) is recorded. Positive and negative interactions between fishery and aquaculture are described for environment, food, juveniles, breeders, discards and market. Special attention is devoted to tuna farming, artificial reef and vallicultura. The response of governments and decision makers to the results and suggestions from marine scientists, proposals for urgent action in order to succeed sustainability and priority marine research areas are briefly described. Some urgent needs are outlined.

On the application of models of European eel (Anguilla anguilla) production and escapement to the development of Eel Management Plans: the River Severn

2007 ◽  
Vol 64 (7) ◽  
pp. 1472-1482 ◽  
Author(s):  
M. W. Aprahamian ◽  
A. M. Walker ◽  
B. Williams ◽  
A. Bark ◽  
B. Knights
Keyword(s):  
Reference Conditions ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Silver Eel ◽  
Management Scenarios ◽  
Test Management ◽  
Management Measures ◽  
Silver Eels ◽  
Management Plans ◽  
The Uk

Abstract Aprahamian, M. W., Walker, A. M., Williams, B., Bark, A., and Knights, B. 2007. On the application of models of European eel (Anguilla anguilla) production and escapement to the development of Eel Management Plans: the River Severn. – ICES Journal of Marine Science, 64: 1472–1482. The European eel stock has declined significantly since the 1980s, and the Eel Recovery Plan of the European Commission requires Member States to develop river basin Eel Management Plans (EMPs) that will achieve an escapement of silver eels that equals or exceeds 40% of the escapement biomass that would be produced in the absence of human activities. However, because silver eel escapement is not quantified within the UK, a modelling approach is required to estimate potential and actual escapement, and to assess the likely effects of management measures. We focus on two approaches developed in the UK, the Reference Condition Model (RCM) and the Scenario-based Model for Eel Populations (SMEP), and illustrate how such approaches can be used in EMPs using selected data from the River Severn. The RCM results indicate that the yellow eel population in the River Severn basin may be just 30–40% of the potential density indicated by reference conditions derived from a selection of rivers between the late 1970s and the early 1980s. The challenges of applying a model designed to be as realistic of eel production as possible, and the limited data on natural eel habitat and eel production in the Severn, preclude a SMEP analysis similar to that of the RCM, but simulations based on a simplified basin description and eel survey data from the early 1980s illustrate the potential of this model to assess compliance and test management scenarios.

scholarly journals First report of a swordfish (Xiphias gladius Linnaeus, 1758) beneath open-sea farming cages in the Western Mediterranean Sea.

2013 ◽  
Vol 15 (1) ◽  
pp. 72 ◽  
Author(s):  
P. ARECHAVALA-LOPEZ ◽  
D. IZQUIERDO-GOMEZ ◽  
P. SANCHEZ-JEREZ
Keyword(s):  
Fish Assemblages ◽  
Management Strategies ◽  
Western Mediterranean ◽  
Adult Individual ◽  
Western Mediterranean Sea ◽  
Ecological Changes ◽  
Open Sea ◽  
Fish Predators ◽  
Xiphias Gladius ◽  
First Time

An adult individual of swordfish (Xiphias gladius L.) was reported for the first time aggregated at coastal Mediterranean fish-farm facilities. This record highlights the necessity to assess the potential ecological changes on wild fish assemblages by coastal farming activity, especially on this type of endangered large migratory fish predators, which might be taken into account for further management strategies.

scholarly journals Coviability analysis of Western Mediterranean fisheries under MSY scenarios for 2020

2014 ◽  
Vol 71 (7) ◽  
pp. 1563-1571 ◽  
Author(s):  
Francesc Maynou
Keyword(s):  
Management Strategies ◽  
Ecosystem Approach ◽  
Fishing Effort ◽  
Western Mediterranean ◽  
Fishing Mortality ◽  
Fish Stocks ◽  
Alternative Management ◽  
Policy Goals ◽  
Management Measures ◽  
Conflicting Objectives

An ecosystem approach to fisheries (EAF) seeks to manage fisheries sustainably, including all dimensions of fisheries: biological, social and economic aspects. The separate management of these aspects may lead to conflicting objectives. Coviability analysis helps us to rank a set of choices (alternative management measures) objectively, allows us to explore which policies will ensure strong sustainability, and formally recognizes the multi-objective nature of fisheries management. The coviability of the main Western Mediterranean Spanish fisheries was examined with a bioeconomic simulation model under alternative management strategies that implement strong fishing mortality reduction policies. Based on a joint (biological and economic) viability assessment, it has been shown that Western Mediterranean fisheries require the reduction of fishing effort to ∼10% of the 2010 levels. This strong conservation measure would need to be applied as soon as possible in order for European Mediterranean fisheries to be managed at MSY, as required by legally binding international agreements, which may be unrealistic. Large reductions in fishing mortality for stocks that have been subject to high exploitation rates for decades are difficult to achieve with the current paradigm of effort control in the Mediterranean. Instead, reorienting the exploitation of Mediterranean fish stocks with management measures that combine changes in exploitation patterns with seasonal or spatial area closures, should help meet the policy goals of fishing mortality levels compatible with MSY by 2020.

scholarly journals Does the Invasive Predator Mnemiopsis leidyi A. Agassiz, 1868 Control Copepod Abundances in the Seine Estuary?

2021 ◽  
Vol 4 (1) ◽  
Keyword(s):  
Spatial Distribution ◽  
Coastal Waters ◽  
Mnemiopsis Leidyi ◽  
Seine Estuary ◽  
English Channel ◽  
Western Atlantic ◽  
Dramatic Decline ◽  
Pleurobrachia Pileus ◽  
Negative Effect ◽  
First Time

The indigenous ctenophore Pleurobrachia pileus (O.F. Müller, 1776) was common in the coastal waters of the English Channel in the early 1990s and showed very abundant populations in the downstream part of the Seine estuary. In 2005, the non-indigenous ctenophore Mnemiopsis leidyi A. Agassiz, 1868, a species native to the Western Atlantic, was reported for the first time in Europe in Norwegian fjords and in Le Havre harbour (Seine estuary, France). More recently, in 2017, both Pleurobrachia pileus and Mnemiopsis leidyi were recorded during suprabenthos and zooplankton sampling in the Seine estuary along a downstream-upstream transect. Both species show more abundant populations in May than in September. Conversely, copepods show a spatial distribution depending on the ctenophore distribution, with low copepod abundances in the downstream part of the estuary being associated with high ctenophore abundances, while high copepod abundances are recorded where ctenophores are absent or display low abundances. We propose that the intense predation of ctenophores on copepods is related to changes in hydrological conditions over the two last decades. This may explain the dramatic decline of copepod abundance in the Seine estuary, which could have a negative effect on its nursery role.

scholarly journals Saving the European Eel: How Morphological Research Can Help in Effective Conservation Management

2020 ◽  
Vol 60 (2) ◽  
pp. 467-475
Author(s):  
Jens De Meyer ◽  
Pieterjan Verhelst ◽  
Dominique Adriaens
Keyword(s):  
Environmental Changes ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Silver Eel ◽  
Critically Endangered Species ◽  
Morphological Studies ◽  
Management Measures ◽  
Migration Barriers ◽  
And Behavior ◽  
The Impact

Abstract The European eel (Anguilla anguilla) is a critically endangered species, whose recruitment stocks have declined to nearly 1% compared to the late 70s. An amalgam of factors is responsible for this, among them migration barriers, pollution, habitat loss, parasite infection, and overfishing. A lot of recent studies focus on aspects that can increase the mature silver eel escapement rate, such as identifying migration barriers and developing passageways or addressing the impact of pollution on the eel’s health. However, little attention is given to the eel’s morphology in function of management measures. Worryingly, less than 50% of the currently installed management plans reach their goals, strongly indicating that more information is needed about the eel’s ecology and behavior. Functional morphological studies provide insights on how species perform behaviors crucial for survival, such as feeding and locomotion, but also in how environmental changes can affect or limit such behaviors. Consequently, functional morphology represents an important biotic component that should be taken into account when making conservation decisions. Hence, here, we provide an overview of studies on the eel’s morphology that do not only demonstrate its relation with ecology and behavior, but also provide information for developing and installing proper and more specific management measures.

Gonad development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.)

2005 ◽  
Vol 55 (3) ◽  
pp. 203-218 ◽  
Author(s):  
Arjan Palstra ◽  
Louise Verschoor ◽  
Vincent van Ginneken ◽  
Olivier Lugten ◽  
Marjolijn Onderwater ◽  
...  
Keyword(s):  
Gonad Development ◽  
Anguilla Anguilla ◽  
Gonadal Development ◽  
Maximum Speed ◽  
European Eel ◽  
Head Region ◽  
Total Period ◽  
Group Spawning ◽  
Spawning Behaviour ◽  
First Time

AbstractGonadal development and spawning behaviour of artificially-matured European eel (Anguilla anguilla L.) was studied. Treatment of males with Human Chorionic Gonadotropin (HCG; 1 IU g/week) resulted in a Gonado-Somatic Index (GSI) of 10.88 ± 3.39 and spermiation. Treatment of females with carp Pituitary suspension (cPs) (20 mg cPs/kg body weight per week) resulted in oogenesis with a GSI of 20.0 ± 11.3 (n = 7), and the number of eggs per female was 1874 * 103 ± 1116 * 103; (n = 7). Ovulation of the females was induced with 17α, 20β dihydroxyprogesteron (DHP) at 2 μg/g bodyweight. Eggs of European eel were found to be non-sticky and typically pelagic. Maximum speed of eggs rising to the surface in a water column was 2.24 ± 0.33 metres (m) per hour (h). To study behaviour in a qualitative way, two females were used together with three groups of three males. During a 283 minute (min) observation of the two females, we observed female-female interaction: 'lethargic behaviour' (33.6%) vs. 'cruising together' (66.4%). In the period when males and females were together (188 min), we observed 'approaching the head region of the female' (57.7%), 'touching the operculum' (39.4%), or 'approaching the urogenital area' (2.9%) by the males (total 725 seconds (s)). Sperm release in the presence of a female took 115 s of the total approaching time of 725 s (15.9%), while in the case of male-male interaction this was only 15 s of the total period of 116 s (12.9%). Induced spawning behaviour of eels was collective and simultaneous, corresponding to spawning in a group. This is the first time group spawning behaviour has ever been observed and recorded in eels.

On the distribution of the European eel (Anguilla anguilla) and its fisheries

2003 ◽  
Vol 60 (7) ◽  
pp. 787-799 ◽  
Author(s):  
Willem Dekker
Keyword(s):  
Meta Analysis ◽  
Anguilla Anguilla ◽  
Western Mediterranean ◽  
Qualitative Description ◽  
Suitable Habitat ◽  
European Eel ◽  
Silver Eel ◽  
Southern Limit ◽  
Glass Eel ◽  
The North

For the distribution of the European eel (Anguilla anguilla), only Schmidt (1909) has conducted substantial investigations, yielding a qualitative description (Atlantic and Mediterranean coasts of Europe and Northern Africa). In this article, a meta-analysis of reported fishing yields is presented, showing a major concentration of glass eel yield in the Bay of Biscay (and possibly farther south) and of yellow and (or) silver eel yield in the western Mediterranean. Fisheries target the glass eel stage at highest stock density and shift to the silver eel stage at low density. Because there is no suitable habitat in the Sahara, the southern limit is, contrary to Schmidt's belief, primarily determined by continental conditions. From the centre of the distribution to the north, a long and slow decline in density occurs. The mismatch between northern temperatures and the species' preference, in combination with the very low abundance, indicates that the European eel is best seen as a warm-water species, like most other eel species (Anguilla spp.), showing a considerable northern diaspora.

scholarly journals New Mediterranean Biodiversity Records (November, 2016)

2016 ◽  
Vol 17 (3) ◽  
pp. 794 ◽  
Author(s):  
CH. MYTILINEOU ◽  
E.H.Kh. AKEL ◽  
N. BABALI ◽  
P. BALISTRERI ◽  
M. BARICHE ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
First Record ◽  
Western Mediterranean ◽  
Distribution Range ◽  
Mnemiopsis Leidyi ◽  
Pterois Miles ◽  
Levantine Sea ◽  
Alien Fish ◽  
The Mediterranean ◽  
First Time

In the present Collective Article information on 26 taxa belonging to 8 Phyla and extended from the western Mediterranean to the Levantine Sea are presented. The new records were found in 9 countries as follows: Spain: first record for the Mediterranean of the crab Cancer bellianus; Algeria: further records of the alien fish Lagocephalus sceleratus to the west Algerian waters; Italy: first report on the presence and establishment of the ctenophore Mnemiopsis leidyi in Lessina and Varano Lagoons (W. Adriatic) and of Penaeus aztecus in Corigliano Gulf (Italian Ionian). Moreover, the extension of the distribution range of the polychaete Branchiomma bairdi to W. Sicily as well as that of the crab Ocypode cursor and the bryozoan Catenicella paradoxa to E. Sicily are cited. Slovenia: the record of the rare saccoglossan gastropod Placida cremoniana from Piran (Gulf of Trieste) is the first for the Adriatic; Greece: the native sea slug Eubranchus farrani is the first from the Eastern Mediterranean; many sightings of the bamboo corals Isididae distributed along all the E. Ionian Sea and the establishment of P. aztecus in all Greek waters are also reported for first time; the westernmost extension of the alien urchin Diadema setosum in Cretan waters is cited and new sights of the alien species Goniobranchus annulatus and Pterois miles are shown. Turkey: the alien fish Champsodon capensis is reported for first time from the Aegean Sea and the native acari Agauopsis microrhyncha from the Levantine Sea; a new observation of the alien crab Atergatis roseus in Güllük Bay-Aegean is also mentioned; Cyprus: first records of  the alien urchin D. setosum and Lobotes surinamensis in Cypriot waters; Lebanon: several sightings of Monachus monachus from the Lebanese waters indicate a potential better status of the species in the area, Egypt: first records of the alien crab Dorippe quadridens and the alien gastropods Nerita sanguinolenta and Conomurex persicus from the Mediterranean Egyptian waters; extension of the distribution range of Diodora funiculata and Diodora rueppellii and a second record of the alien Nerita sanguinolenta in the same area.  

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